Lin Huang, Ji-Wan Kim, Sang-Hyuk Lee, Seon-Dae Kim, Van Manh Tien, Kiran Prakash Shinde, Je-Ho Shim, Yooleemi Shin, Hee Jun Shin, Seongheun Kim, Jaehun Park, Seung-Young Park, Yeon Suk Choi, Hyun-Joong Kim, Jung-Il Hong, Dong Eon Kim, Dong-Hyun Kim
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| Schematic diagram of THz emission and detection by the electro-optic (EO) sampling method. The dotted box area is zoomed to show the sample region with the axis configuration. |
We have experimentally investigated the field- and fluence-dependent terahertz (THz) emission behaviors by a femtosecond optical pump in Co ferromagnetic films, together with the time-resolved magneto-optical Kerr effect measurement. The thickness of Co and Ta capping layers has been systematically varied. For thick films, THz emission behavior is found to be directly matched with the photoinduced ultrafast demagnetization and remagnetization dynamics. The angle-dependent THz emission measurement also confirms a direct relation between the THz emission and the photoinduced demagnetization/remagnetization dynamics in the case of thick films, while THz emission from the inverse spin Hall effect also plays a role in the case of thin Co films.
This work was supported by the Korea Research Foundation (NRF) (Grant Nos. 2018R1A2B3009569 and 2017R1A6A3A04011173) and by KBSI Grant No. D39614. This work was also supported in part by the Global Research Laboratory Program (Grant No. 2009-00439) and by the Max Planck POSTECH/KOREA Research Initiative Program (Grant No. 2016K1A4A4A01922028) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning.
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